First of all, sorry if I didn't write some words well, english is not my mother tongue. Having said that, let's start with this guide.

Master Yi is a very easy champ, but you can feed the enemies if you don't do well the combos or if you dont use the correct runes and items. He has a lot of damage on early with lethal tempo because the attack speed this brings to you. With this you can win the 1v1 even on hard matchups.

The mid-game is your best moment. There is when you're stronger (and more if you've already buy the Blade Of The Ruined King and Frozen Mallet) and when need to feed and finish the game, because in late-game your damage and sustain decays a little and yes, that's why you need the Frozen Mallet, a core item, and the Bloodthirster. With this 2 items you will not be raped but don't be a crazy and suicide in a 1v5.

An anecdote, when I started playing League of Leyends I started as a jungle, and with Master Yi (as a lot of people) and my friends always maked jokes, but I only used it until I reached lvl 100, so I learned a lot, more than the "easy yi noob champ gg". I know that maybe Master Yi does not need a guide, but these are the regular Yi. This Yi is GOD. I assure you

I reccomend to start with Q now that it got a buff. As you can evade 2 basic attacks with E if you're Jax and if you do it in the right moment, with Master Yi you can use Q when the autoattack animation of the monster starts and delay damage.
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You should star at marker 1 (red buff). If you see the image you will see the red arrows marking the jungle route. At the yellow arrows and "X" I point the best gank options. At number 1 you can do a lvl 2 gank 2v1 to the lvl 1 enemy mid and get the first blood. At marker 4 (or even 5) you can gank mid again. A tip, always try to secure your blue Rift Scuttler (it spawns just when you finish killing your blue) At marker 5 (Rift Scuttler) you can also gank top. At marker 7 you can gank bot if you see it possible and secure drake.
(Of course, if you are in the red side just turn the map)



That's all for now, if you have a comment or suggest tell me and I update/fix/test.